Diamond SOI, Silicon-on-Diamond-on-Silicon (SODOS), Diamond-on-Silicon, and Thin Silicon-on-Thick Diamond process technologies are being developed to enhance heat flow through the substrate for use in high power devices. In the case of SODOS, the buried diamond layer is used as a heat sink—a heat spreader that reduces the temperature of semiconductor devices operating at high power in the device silicon above. Thermal conductivity of diamond is 10× better than silicon and 1000× better than oxide.
Despite high-purity components used in the HFCVD reactor (Hot Filament Chemical Vapor Deposition), elevated levels of mobile heavy metal ions have been found to out-diffuse from the diamond and seed layer into the adjacent device silicon layer, thus degrading the quality of the silicon and reducing electron and hole current carrier lifetime. During subsequent diffusion operations these ions can out-diffuse from the diamond and silicon layers and cross-contaminate fabrication processing equipment.
An improved diamond SOI device and method of forming the same would be desirable, in which a barrier can be formed between the diamond SOI layer and the device silicon layer to block diffusion of ions and improve carrier lifetime of the device silicon.
It should be noted that some details of the figures have been simplified and are drawn to facilitate understanding of the inventive embodiments rather than to maintain strict structural accuracy, detail, and scale.